From the San Francisco Chronicle:
“When Albert Salvador, Cupertino’s building official, visited Apple’s new spaceship building last year, he worried that people would walk into the cafeteria’s glass walls because they couldn’t distinguish them from the equally clear automatic doors.
After he brought up the issue, a contractor walked straight into the glass.
He would not be the last.”
I’m pretty sure that Apple knows that people walking (or barging) into glass panes could cause serious (but sometimes hilarious) hurt.